Currently after an anchor is set to hold an open hole whipstock in place, the running tool is released from the whipstock by dropping a ball and applying hydraulic pressure against the ball to shift a piston. After the piston is displaced a collet on the running tool will deflect inward and allow the running tool to be removed from the whipstock. The requirement to drop the ball from surface means that Measurement While Drilling (MWD) cannot be used to orient the whipstock. The improved system allows the running tool to be disengaged from the whipstock without dropping a ball from surface.
The pump through Bigfoot Anchor made by Baker Hughes Incorporated was created so that cement can be pumped through the whipstock on the same run that the anchor is set. This is done by lowering the whipstock assembly to depth and then using wireline to lower a gyro into the assembly to orient the face of whipstock. After the whipstock is oriented the gyro is retrieved to surface. A ball is then dropped from surface so that hydraulic pressure can be applied against the ball to move a piston to set the anchor. Pressure is then increased until a rupture disc is broken. A second ball is dropped so that hydraulic pressure can be applied to shift a piston that is supporting a collet that attaches the running tool to the whipstock. After the running tool is released cement can be pumped through the rupture disc to cement the anchor in place. This system is limited by the fact that balls must be dropped from surface, which prevents the use of MWD. Because gyros are run on wireline they cannot be used on highly deviated or horizontal wells. The present invention modifies the pistons in the anchor and whipstock so that they can be activated by using pressure drop though nozzles to break the shear screws that hold the pistons in place. A whipstock valve is added to the system. With the new configuration a ball is on seat in the pump through Bigfoot Anchor when tripping in hole. The whipstock valve provides a flow path to the annulus. After MWD has oriented the face of the whipstock, flow rate is increased to break the shear screws in the whipstock valve so that the annular ports can be closed. Pressure can now be applied to set the anchor. After the anchor has been set a flow path to the annulus is created. This can be done by extruding the ball through the ball seat, having the ball seat release from the piston assembly, or opening a rupture disc. Once the flow path is created pressure drop through a nozzle in the piston in the whipstock will break the shear screws holding the piston in place. This will release the collet holding the running tool in place. Cement can now be pumped through the port in the anchor to cement the anchor in place. Debris could be a problem with this solution. Since the whipstock valve is the only flow path to the annulus fluid cannot be pumped through the anchor to displace debris when lowering the assembly into the hole.
Another solution would be to not have a ball on seat in the anchor when positioning the assembly into the well. That is, the anchor is set by pressure drop through a nozzle, and the running tool is also released by pressure drop through another nozzle. This allows flow all the way through the anchor, and will reduce the debris issue. The problem with this solution is that the anchor activation must happen at a higher flow rate that is required for MWD readings, and an even higher flow rate is required to shift the piston to release the running tool from the whipstock. To make sure that the anchor is set securely requires 3,000 psi pressure acting on the piston. An even higher pressure will be created when the flow rate is increased to shift the piston that releases the running tool. When adding these two pressure requirements to pressure drop through the drill string, standpipe pressure at surface could be higher than is desired.
Various configurations are envisioned that are flow sensitive for sequential settings of the anchor and subsequent release of the collets holding the running tool to the whipstock. Cement placement through the anchor is enabled with the running tool released from the whipstock so that it can be removed after cementing the anchor. Flow for MWD orientation purposes for the whipstock is enabled as are sequential operation of the anchor and then the release of the running tool while keeping the running tool in position to deliver cement and release from the whipstock. No balls are needed, which would impeded the operation of the MWD unit in orienting the whipstock. These and other aspects of the present invention will be more readily understood from a review of the description of the preferred embodiment and the associated drawings while recognizing that the full scope of the invention is to be determined from the appended claims.